1. Field of the Invention
The present invention relates to an operating method for an absorption heat pump, and in particular to an operating method of an absorption heat pump which is capable of obtaining a stable and high COP(Coefficient Of Performance) by changing a heat exchange amount using a filter based on a density estimated by a temperature of a refrigerant vapor flown into a condenser and obtaining a high purity and density of a refrigerant vapor.
2. Description of the Background Art
Generally, an absorption heat pump uses a LNG, LPG, gasoline, etc. as a heat source unlike a vapor compression type pump which uses an electric power as a heat source. The above-described absorption heat pump is a cooling, warming and heating system by generating a cooled or heated water based on a heat driven heat pump using a combustion heat as a heat source.
As an example of an absorption heat pump, FIG. 1 illustrates the construction of a conventional ammonia GAX(Generator Absorber heat eXchanger) which uses an ammonia solution as an absorbing agent.
The operation that the ammonia GAX absorption heat pump is operated based on a cooling cycle as shown in Figure will be explained. First, when the heat generated by a burner(not shown) is transferred to a gas direct burning generator 1, a rich solution having a high ammonia density is heated and is changed to a refrigerant vapor and dilute solution. The thusly generated refrigerant vapor is flown into an analyzer 3 and a rectifier 4 installed above the solution heat exchanger 2 for increasing a refrigerant density through the solution heat exchanger 2 installed above a direct-fired type generator 1 in order to decrease the load of the generator 1.
In detail, in the above-described heating operation, since a difference between the heating points of the ammonia and water is small, the ammonia and water are heated together, so that a filtering process for removing a vapor component from the refrigerant vapor is adapted so as to use a pure ammonia as a refrigerant. The analyzer 3 and rectifier 4 are used to implement the above-described filtering operation.
The refrigerant vapor passed through the solution heat exchanger 2 is flown into the interior of the analyzer 3 filled with a filling agent and contacts with a low temperature rich solution supplied from a water cooling absorber 5 to the analyzer 3 through the rectifier 4, so that a vapor component is condensed.
The refrigerant vapor condensed as the vapor component is condensed is flown into the interior of the rectifier 4. At this time, the vapor component which is not condensed by the analyzer 3 by a heat exchange with the low temperature rich solution supplied from the water cooling absorber 5 to the rectifier 4 through the solution pump 6 is condensed, so that the refrigerant vapor is filtered.
The refrigerant vapor flown into the condenser 7 through the above-described filtering operation is condensed into a liquid refrigerant based on a heat exchange with a cooling water by the condenser 7 and is flown into a pre-cooler 8.
Continuously, the refrigerant vapor has a temperature decreased to the vapor temperature of the evaporator 9 by a heat exchange with the refrigerant vapor passed through the evaporator 9 and passes through an expansion valve 14 and is flown into the evaporator 9 in a vapor state. Thereafter, the temperature is increased by an indoor unit(not shown), and the refrigerant is vaporized by a heat exchange with a cooled water flown into the evaporator 9.
At this time, the cooled water having a temperature decreased by an evaporation latent heat is flown into the indoor unit and decreases the temperature of the air of the indoor.
Thereafter, The refrigerant vapor vaporized by the vaporizer 9 is flown into the pre-cooler 8, and the temperature of the same is increased up to the temperature of a condensing liquid from the condenser 7 by a heat exchange with the liquid state refrigerant condensed by the condenser 7 and is flown into the GAX 10, the solution cooling absorber 12, and the water cooling absorber 5.
In addition, the solution remained by generating a refrigerant, namely, the dilute solution having a low ammonia density is flown into the solution heat exchanger 2 and is heat-exchanged with a rich solution which is downwardly flown, so that the temperature is decreased. Thereafter, the resultant solution is flown into the GAX 10 in a state that the pressure of the same is decreased by a pressure decreasing valve 11 and passes through the GAX 10, the solution cooling absorber 12, and the water cooling absorber 5 and absorbs a refrigerant vapor from the evaporator 9 and is changed into a rich solution having a high density ammonia.
In detail, the dilute solution which absorbs a refrigerant vapor at the GAX 10 and the solution cooling absorber 12 has a temperature decreased by a heat exchange with the rich solution circulated by the solution pump 6 through the water cooling absorber 5. The temperature of the same is further decreased by a heat exchange with a cooled water passed through a radiator(not shown) in the water cooling absorber 5.
In addition, the rich solution generated by the water cooling absorber 5 is supplied to the rectifier 4 by the solution pump 6, and the flowing amount of liquid is properly controlled by a flowing liquid amount control three-way valve 13 and is flown into the solution cooling absorber 12 and the analyzer 3.
In detail, the rich solution flown into the solution cooling absorber 12 is heated and boiled by an absorption heat generated when a refrigerant vapor is absorbed into the dilute solution, and a vapor state liquid is supplied to the upper portion of the solution heat exchanger 2. A part of the liquid is heat-exchanged with the dilute solution flowing in the solution heat exchanger 2, so that the temperature of the same is increased, and the liquid is downwardly flown in the direction of the generator 1.
The rich solution flown toward the upper portion of the analyzer 3 contacts with a refrigerant vapor upwardly moving from the generator 1 and absorbs a part of the vapor included in the refrigerant vapor and filters the same and is downwardly flown in the direction of the generator 1.
Therefore, the above-described operation is repeatedly performed during the operation of the system.
On the contrary, in the heating cycle operation, the flowing direction of the cooling water is changed and is flown toward the radiator(not shown) of the outdoor unit through the evaporator 9. The cooling water is flown toward the indoor unit through the condenser 7 and the cooling water absorber 5. At this time, the high temperature water which absorbed the condensing heat and absorption heat radiates heat in the indoor unit, so that an indoor air is heated for thereby performing a heating operation.
In the above-described absorption heat pump, the cooling COP and heating COP are greatly changed in accordance with the density of the refrigerant vapor flown from the rectifier to the condenser.
As shown in FIG. 2, when the density of the ammonia used as a refrigerant is 97%, the cooling COP is 0.65, and the heating COP is 1.55. When the density of the ammonia is 99%, the cooling COP is 0.74, and the heating COP is 1.64.
Namely, as the density of the ammonia is increased by 2%, the cooling COP is increased by 13%, and the heating COP is increased by 5%.
Therefore, in order to obtain an excellent performance, the rectifier which is capable of increasing the density of the refrigerant is important. The density of the refrigerant preferably has above 99.5%.
However, in the conventional absorption heat pump, if the load or outdoor temperature is changed, the density of the ammonia, namely, the density of the refrigerant is decreased, so that the COP of the system is decreased.
FIG. 3 illustrates a density variation characteristic of the refrigerant vapor and liquid refrigerant from an inlet portion to an outlet portion of the evaporator.
In this case, if the refrigerant density is low, it means that a lot amount of water components(H2O) is included in the liquid refrigerant flown into the evaporator.
Therefore, in the evaporator structure in which a refrigerant is flown from the lower portion of the heat exchange coil and flown to the upper portion of the same, when the system operates for long time, the water components are gathered at the lower portion, so that the density(purity) of the refrigerant is decreased for thereby decreasing the performance of the evaporator, whereby a bleeding phenomenon occurs.
In addition, in order to prevent the bleeding phenomenon, the water component gathered at the lower portion of the evaporator must be manually removed.
Accordingly, it is an object of the present invention to provide an operation method of an absorption heat pump capable of obtaining a high purity and density of a refrigerant vapor and a high and stable COP even when a load and an outdoor temperature are changed by changing the amount of a heat exchange performed by a rectifier in accordance with the density of a refrigerant estimated by a temperature of a refrigerant vapor flown into a condenser.
To achieve the above objects, there is provided an operation method of an absorption heat pump according to the present invention which includes a step for measuring a temperature of a refrigerant vapor passed through the above-described rectification process, a step for comparing the measured temperature and a previously set temperature and estimating a refrigerant density passed through the rectification process, and a step for controlling a heat exchange amount between a rich solution and a refrigerant vapor during the rectification process based on the estimated refrigerant density.
Additional advantages, objects and features of the invention will become more apparent from the description which follows.